I. Field
The present invention relates generally to communication, and more specifically to techniques for processing data in a multiple-antenna communication system.
II. Background
A multi-antenna communication system employs multiple (NT) transmit antennas and one or more (NR) receive antennas for data transmission. The NT transmit antennas may be used to increase system throughput by transmitting different data from the antennas or to improve reliability by transmitting data redundantly.
In the multi-antenna communication system, a propagation path exists between each pair of transmit and receive antennas. NT·NR different propagation paths are formed between the NT transmit antennas and the NR receive antennas. These propagation paths may experience different channel conditions (e.g., different fading, multipath, and interference effects) and may achieve different signal-to-noise-and-interference ratios (SNRs). The channel responses of the NT·NR propagation paths may thus vary from path to path. For a dispersive communication channel, the channel response for each propagation path also varies across frequency. If the channel conditions vary over time, then the channel responses for the propagation paths likewise vary over time.
Transmit diversity refers to the redundant transmission of data across space, frequency, time, or a combination of these three dimensions to improve reliability for the data transmission. One goal of transmit diversity is to maximize diversity for the data transmission across as many dimensions as possible to achieve robust performance. Another goal is to simplify the processing for transmit diversity at both a transmitter and a receiver.
There is therefore a need in the art for techniques to process data for transmit diversity in a multi-antenna communication system.